Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1020993 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR26215746_1.fastq.gz | Fastqsanger.gz | |||
| SRR26215746_2.fastq.gz | Fastqsanger.gz | |||
| SRR26215747_1.fastq.gz | Fastqsanger.gz | |||
| SRR26215747_2.fastq.gz | Fastqsanger.gz | |||
| SRR26215748_1.fastq.gz | Fastqsanger.gz |
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Project description:Temozolomide (TMZ) has been used for the treatment of glioblastoma (GBM) since last decade, but its treatment benefits are limited by acquired resistance, a process that remains incompletely understood. Here we report that a novel enhancer, located between the promoters of Ki67 and O6-methylguanine-DNA-methyltransferase (MGMT) genes, is activated in TMZ-resistant patient-derived xenograft (PDX) lines as well as in recurrent tumor samples. Activation of the enhancer correlates with increased MGMT expression, a major known mechanism for TMZ resistance. We show that forced activation of the enhancer in cell lines with low MGMT expression results in elevated MGMT expression. Deletion of this enhancer in cell lines with high MGMT expression leads to reduced levels of MGMT and Ki67, increased TMZ sensitivity and impaired proliferation. Together, these studies uncover a novel mechanism that regulates MGMT expression, confers TMZ resistance and potentially regulates tumor proliferation.
2018-07-13 | GSE113816 | GEO
Project description:N6-methyladenosine (m6A) is a critical regulator of mRNA processing and function, playing roles in mRNA processing, translation, and decay. Changes in m6A status have been implicated in various cancers, including glioblastoma (GBM), where acquired chemoresistance to temozolomide (TMZ) remains a major clinical challenge. We developed cell culture models of acquired TMZ resistance in GBM and analyzed the regulation of resistance-associated genes and pathways by m6A. We find that key resistance-associated genes and pathways are regulated by m6A methylation, including MGMT, the enzyme that repairs primary TMZ-induced DNA damage. Inhibition of METTL3 with STM2457 treatment destabilizes MGMT mRNA. Intriguingly, other TMZ resistance-associated genes are similarly regulated by m6A, suggesting that METTL3 inhibition may represent a promising therapeutic approach for overcoming TMZ resistance.
2026-06-01 | GSE306559 | GEO
Project description:N6-methyladenosine (m6A) is a critical regulator of mRNA processing and function, playing roles in mRNA processing, translation, and decay. Changes in m6A status have been implicated in various cancers, including glioblastoma (GBM), where acquired chemoresistance to temozolomide (TMZ) remains a major clinical challenge. We developed cell culture models of acquired TMZ resistance in GBM and analyzed the regulation of resistance-associated genes and pathways by m6A. We find that key resistance-associated genes and pathways are regulated by m6A methylation, including MGMT, the enzyme that repairs primary TMZ-induced DNA damage. Inhibition of METTL3 with STM2457 treatment destabilizes MGMT mRNA. Intriguingly, other TMZ resistance-associated genes are similarly regulated by m6A, suggesting that METTL3 inhibition may represent a promising therapeutic approach for overcoming TMZ resistance.
2026-06-01 | GSE306560 | GEO
Project description:Patients diagnosed with glioblastoma (GBM) with sustained synthesis of the DNA repair enzyme, O6-methyl guanine DNA methytransferase (MGMT), are rendered resistant to Temozolomide (TMZ) chemotherapy. Here, we hypothesized that pretreatment with the proteasome inhibitor Bortezomib (BTZ, Velcade) might sensitize these GBM to TMZ by depleting MGMT.
2019-08-20 | PXD007193 | Pride
Project description:Acquired resistance of temozolomide (TMZ) is one of the major obstacle of glioblastoma clinical treatment and the mechanism of TMZ resistance is still not very clear. In the presented research we show that deletion of rs16906252-associated MGMT enhancer in MGMT negative glioma cells induced increase sensitivity to temozolomide and combination of RNA-seq and Capture HiC identified several long-range target genes of rs16906252-associated MGMT enhancer. In addition, HiC data shows alterations of chromatin structures in glioma cells survived from high-dosage TMZ treatment and changes of TADs influence rs16906252-associated MGMT enhancer’s long-range regulations of target genes. Our study suggests rs16906252-associated MGMT enhancer regulates glioma cells’ TMZ sensitivity by long-range regulations of several target genes, which is a novel mechanism of regulation of TMZ sensitivity in glioma cells.
2020-04-02 | GSE129476 | GEO
Project description:Temozolomide (TMZ) is an important first-line treatment for glioblastoma (GBM), but there are limitations to TMZ response in terms of durability and dependence on the promoter methylation status of the DNA repair gene O6-methylguanine DNA methyltransferase (MGMT). MGMT-promoter-hypermethylated (MGMT-M) GBMs are more sensitive to TMZ than MGMT-promoter-hypomethylated (MGMT-UM) GBMs. Moreover, TMZ resistance is inevitable even in TMZ-sensitive MGMT-M GBMs. Hence, epigenetic reprogramming strategies are desperately needed in order to enhance TMZ response in both MGMT-M and MGMT-UM GBMs. In this study, we present novel evidence that the epigenetic reactivation of Tumor Suppressor Candidate 3 (TUSC3) can reprogram sensitivity of GBM stem cells (GSCs) to TMZ irrespective of MGMT promoter methylation status. Interrogation of TCGA patient GBM datasets confirmed TUSC3 promoter regulation of TUSC3 expression and also revealed a strong positive correlation between TUSC3 expression and GBM patient survival. Using a combination of loss-of-function, gain-of-function and rescue studies, we demonstrate that TUSC3 reactivation is associated with enhanced TMZ response in both MGMT-M and MGMT-UM GSCs. Further, we provide novel evidence that the demethylating agent 5-Azacitidine (5-Aza) reactivates TUSC3 expression in MGMT-M GSCs, whereas the combination of 5-Aza and MGMT inhibitor Lomeguatrib is necessary for TUSC3 reactivation in MGMT-UM GSCs. Lastly, we propose a pharmacological epigenetic reactivation strategy involving TUSC3 that leads to significantly prolonged survival in MGMT-M and MGMT-UM orthotopic GSCs models. Collectively, our findings provide a framework and rationale to further explore TUSC3-mediated epigenetic reprogramming strategies that could enhance TMZ sensitivity and outcomes in GBM. Mechanistic and translational evidence gained from such studies could contribute towards optimal design of impactful trials for MGMT-UM GBMs that currently do not have good treatment options.
2024-11-26 | GSE282886 | GEO
Project description:Temozolomide (TMZ) is an oral alkylating agent used for the treatment of glioblastoma and is now becoming a chemotherapeutic option in patients diagnosed with high-risk low-grade gliomas. The O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for the direct repair of the main TMZ-induced toxic DNA adduct, the O6-Methylguanine lesion. MGMT promoter hypermethylation is currently the only known biomarker for TMZ response in glioblastoma patients. Here we show that a subset of recurrent gliomas carry MGMT genomic rearrangements that lead to MGMT overexpression, independently from changes in its promoter methylation. By leveraging the CRISPR/Cas9 technology we generated some of these MGMT rearrangements in glioma cells and demonstrated that they lead to TMZ resistance both in vitro and in vivo. Lastly we showed that such fusions can be detected in tumor-derived exosomes and could potentially represent an early detection marker of tumor recurrence in a subset of patients treated with TMZ.
| EGAD00001006281 | EGA
Project description:Temozolomide (TMZ) is an oral alkylating agent used for the treatment of glioblastoma and is now becoming a chemotherapeutic option in patients diagnosed with high-risk low-grade gliomas1. The O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for the direct repair of the main TMZ-induced toxic DNA adduct, the O6-Methylguanine lesion. MGMT promoter hypermethylation is currently the only known biomarker for TMZ response in glioblastoma patients2. Here we show that a subset of recurrent gliomas carry MGMT genomic rearrangements that lead to MGMT overexpression, independently from changes in its promoter methylation. By leveraging the CRISPR/Cas9 technology we generated some of these MGMT rearrangements in glioma cells and demonstrated that they lead to TMZ resistance both in vitro and in vivo. Lastly we showed that such fusions can be detected in tumor-derived exosomes and could potentially represent an early detection marker of tumor recurrence in a subset of patients treated with TMZ.
| EGAS00001004544 | EGA
Project description:Temozolomide (TMZ) increases the overall survival of patients with glioblastoma (GBM), but its role in the clinical management of diffuse low-grade gliomas (LGG) is still being defined. DNA hypermethylation of the O 6 -methylguanine-DNA methyltransferase (MGMT) promoter is associated with an improved response to TMZ treatment, while inactivation of the DNA mismatch repair (MMR) pathway is associated with therapeutic resistance and TMZ-induced mutagenesis. We previously demonstrated that TMZ treatment of LGG induces driver mutations in the RB and AKT-mTOR pathways, which may drive malignant progression to secondary GBM. To better understand the mechanisms underlying TMZ-induced mutagenesis and malignant progression, we explored the evolution of MGMT methylation and genetic alterations affecting MMR genes in a cohort of 34 treatment-naïve LGGs and their recurrences. Recurrences with TMZ-associated hypermutation had increased MGMT methylation compared to their untreated initial tumors and higher overall MGMT methylation compared to TMZ-treated non-hypermutated recurrences. A TMZ-associated mutation in one or more MMR genes was observed in five out of six TMZ-treated hypermutated recurrences. In two cases, pre-existing heterozygous deletions encompassing MGMT, or an MMR gene, were followed by TMZ-associated mutations in one of the genes of interest. These results suggest that tumor cells with methylated MGMT may undergo positive selection during TMZ treatment in the context of MMR deficiency.
| EGAS00001001179 | EGA
Project description:Glioblastoma (GBM) invariably develops resistance to temozolomide (TMZ), the frontline chemotherapeutic agent, leading to treatment failure. The molecular mechanisms underlying this resistance remain incompletely understood. Here, we identify karyopherin subunit alpha 3 (KPNA3) as a novel and critical driver of TMZ resistance. Through integrated bioinformatics analysis of temozolomide-resistant glioma cells (SF126R) and patient databases, we found KPNA3 expression is elevated in TMZ-resistant contexts and correlates with poor prognosis in TMZ-treated patients. Functional studies demonstrated that KPNA3 knockdown in resistant cells impaired malignant behaviors, re-sensitized cells to TMZ-induced apoptosis, and suppressed glioma stem cell (GSC) properties, including sphere formation and expression of stemness factors (OCT4, ALDH1A1). Mechanistically, KPNA3 promotes resistance via a dual pathway: it upregulates the expression of the DNA repair enzyme MGMT and activates the STAT3 signaling pathway. KPNA3 knockdown reduced both MGMT levels and STAT3 phosphorylation (Tyr705). Furthermore, pharmacological inhibition of STAT3 mirrored the effect of KPNA3 knockdown by potently inhibiting GSC generation. Clinically, KPNA3 and p-STAT3 protein levels were positively correlated in high-grade glioma tissues. Collectively, our findings unveil KPNA3 as a central regulator that concurrently enhances DNA repair and sustains the GSC population to foster TMZ resistance, nominating it as a promising therapeutic target for overcoming chemoresistance in GBM.
2026-07-17 | GSE327029 | GEO